Topographic representations of the built environment of cities tend to emphasize the distinctiveness of the various socio-economic sectors: the differences between poor and rich neighborhoods, between commercial and manufacturing districts, and so on. While valid, this type of representation of a city is partial because there are a variety of underlying connections. Further, it may even be more problematic than in the past, given some of the socio-economic, technical, and cultural dynamics of the current era. One step towards understanding what constitutes the complexity of large cities is the analysis of interconnections among urban forms and fragments that present themselves as unconnected.

The Informal City in "Advanced" Urban Economies.

The corporate complex and the immigrant community today are probably two extreme modes in the formation and appropriation of urban space in global cities of the North. In major complex cities of the South, including global cities, we see the informal city rather than the “immigrant community”. Globalization has brought about an often massive development of the corporate economic built environment in these cities of the South, as is evident in Mumbai, Shanghai, Sao Paulo, Mexico City, Bangalore, and so on.

The urban form represented by the global city function – the internationalized corporate services complex and the highly paid professional workforce with its high-priced lifestyle spaces – is the one habitually thought to constitute the essence of an advanced post-industrial economy. The urban form represented by the immigrant community, or the informal city, is habitually seen as not belonging to an advanced economy, one to be found in the global cities of the North only because it is imported via immigration, and in the cities of the South as a sign of underdevelopment.

These two forms reveal how power and the lack of power inscribe themselves in the urban landscape and which narratives are attached to each. One is seen as representing technological advance and cosmopolitan culture, the other, economic and cultural backwaters. One presents itself as part of the global economy, suffused in internationalism; the other, while international in its origin, is promptly reconstituted as a local, vernacular form. One is read to be dis-embedded, transterritorial to the point of being thought of as a-spatial, captured by concepts such as the information economy and telematics. The other is read as deeply embedded in an economic, social and cultural territory of neighborhoods and particularistic traditions that have little if any conncetion with the advanced corporate sector.
However, the informal economy and, more generally, certain "working class" uses of space are actually also forms through which advanced economies function and materialize in urban space.

Many of the highly differentiated components of the economy – whether firms, sectors, or workers – are actually interconnected, but with often extreme social, economic, racial and organizational segmentation. The result is fragmented topographies that obscure the underlying connections. This segmentation is regularly strengthened, and even enabled, through racism and discrimination. Ethnic/ racial segmentation not only produces economic outcomes that devalue some firms and workers and over-value others, but also produces a narrative about the nature of our large cities which marginalizes the economics and the culture of non-dominant sectors.

Cities as production sites for global control capacities.

Complex cities, especially if global cities, are production sites for a large array of inputs and "organizational commodities" necessary for global control and coordination. The key point from the perspective of the interdependencies underlying what appear as fragmented topographies is that these inputs need to be produced. The producer services sector is a sort of new basic industry - it ranges form advanced corporate services such as finance and accounting to industrial services like trucking and warehousing. Major cities are preferred sites of production for the specialized services that firms need. But firms in the advanced sector also create a demand for industrial services - the software used by the financiers and accountants needs to be trucked. Further, the lifestyles of the new professional classes create a large demand for goods and services, often made and delivered through low wage workers. These do not seem to be part of the advanced economy, but they are.

Focusing on the production of these various services helps us see the many different types of firms, workers and neighborhoods that are actually part of the advanced urban economy. Furthermore, it helps us focus on the organization of globalized economic sectors: outsourcing, subcontracting, supply chains, networks, or input and output markets. All of this allows us to see that much of this work happens partly in the informal economy of these cities. Thus the existence of a dynamic growth sector feeds the expansion of what appear to be declining or backward economic sectors, such as the downgraded manufacturing sector and the informal economy.

Even the most sophisticated professional sectors need access to a broad range of industrial services located in easy access in central areas. When these lower profit firms lack the bidding power to locate in central areas they often operate partly or fully in the informal economy. Further, the growing inequality in the distribution of household income and firms’ profits reorganizes consumption and life-styles. High income households and newly gentrified residential areas require more services, often through informal workers. But also the growing numbers of low-income households – or firms - are likely to meet more and more of their needs through the informal economy, albeit through a different component of it.

Finally, a question bringing these different strands together is that of the effect of economic restructuring (in its many guises) on the organization of the capital-labor relation. Informalization of economic activities and downgrading of manufacturing in particular (e.g. going from unionized factories to semi-informal operations) are, in the end, modes of reorganizing the relationship between capital and labor in an advanced urban economy with enormous differentials in the profit-making capacities of different types of firms and sectors. Through this reorganization these low-profit sectors are actually incorporated into the advanced economy. But it just does not look like it. The changes in the sphere of social reproduction described above also add to this reorganization insofar as consumption and life-style have contributed to a proliferation of small, labor intensive firms. Some of these cater to high-income households and others cater to very low-income households. Both however share the fact that they have a distinct form of organizing work, quite different from the large-scale, standardized firm where unionization and adherence to various regulations are more typical.

One effect of all of this is the proliferation of small firms, including interestingly an expansion in labor-intensive and informal types of manufacturing in the city, even as large standardized factories leave the city. I like to think of this as “urban manufacturing” – a kind of networked manufacturing, dependent on contractors and subcontractors, and mostly servicing service firms and housheolds. This inverts the historic relationship whereby services serviced manufacturing. These small firms become more typical at the same time that global market firms dominate the city's economy.

One fundamental form of the interaction of space, production, and social reproduction in our “advanced” cities is the growing demand for both luxury housing and low-price housing. Displacement of more modest households, including the lower ends of the middle class, is common in all global cities around the world. So are conflicts over access to city land. But pushing out the low-wage workers does not make sense: if their trip to work becomes unacceptably long or costly, those highly dynamic sectors with a critical mass of both high- and low-income jobs will suffer – and they are likely to bring income to city government. The informal city of work and housing and daily services, can then be seen as a strategic component of advanced urban economies.

New Frontier Zones: The formation of new political actors

The other side of the large complex city, especially if global, is that it is a new “frontier zone” where an enormous mix of people converge. Those who lack power, those who are disadvantaged, outsiders, discriminated minorities, can gain presence in such cities, presence vis a vis power and presence vis a vis each other. This signals the possibility of a new type of politics centered in new types of political actors. It is not simply a matter of having or not having power. There are new hybrid bases from which to act.

Here the interaction between fragmented topographies and the existence of underlying interconnections assume a very different form: what presents itself as segregated or excluded from the mainstream core of a city is actually an increasingly complex political presence. The space of the city is a far more concrete space for politics than that of the nation. Here, non-formal political actors who are rendered invisible in national politics, have better access to the political scene. And, perhaps more importantly, they can constitute themselves as political actors. The fact itself that the new advanced urban economy generates a vastly expanded luxury zone that displaces other firms and homes becomes a fact feeding politics. Urban space is no longer civic, as old local ruling elites aspired to: today it is political. Much of urban politics is concrete, enacted by people rather than dependent on massive media technologies. Street level politics makes possible the formation of new types of political subjectivity, which are not dependent on the formal political system, as is the case with electoral systems.

Further, the Internet can strengthen a new type of cross-border political activism, one centred in multiple localities, reflecting local struggles and initiatives, yet intensely connected digitally with other such localities around the city, the country, the world. This is a politics of the local but with a big difference. Digital networks are contributing to the production of new kinds of interconnections underlying what appear as fragmented topographies, whether at the global or at the local level. A poor neighborhood may look isolated and out of the loop, but may in fact be deeply connected to other such neighborhoods and larger institutions. Political activists can use digital networks for global or non-local transactions and they can use them for strengthening local communications and transactions inside a city or rural community.

The large city of today, especially the global city, emerges as a strategic site for these new types of operations. It is a strategic site for global corporate capital: the urban moment turns that elusive category that is global corporate capital into actual men and women who wanted it all and grab it all. In so doing they become visible as a social force with a distinct project, a project that also has an urban shape. But it is also one of the sites where the formation of new claims by informal political actors is given shape, and materializes in concrete forms. Under these conditions, the enormous mixity of the disadvantaged also takes the shape of a social force. These are two new actors on the scene of history: and it is in the city that they encounter each other and become political.

Saskia Sassen is Professor at the University of Chicago, and Centennial Visiting Professor at the London School of Economics. Her new book is Territory, Authority and Right: From Medieval to Global Assemblages (Princeton University Press, 2006). She has just completed for UNESCO a five-year project on sustainable human settlement for which she set up a network of researchers and activists in over 30 countries.